Filament connection for electric incandescent lamps



Feb. 22, 1949. LEI'GH ON 2,462,325

F-ILAMENT CONNECTION FOR ELECTRIC INCANDE SCENT LAMPS Filed July 12. 1947 Flgz. Z3

1'i l fl I '1 lnvervkor: 30 Leroy G. Leighton,

a I 32 v 27 His At lier-neg.

Patented Feb. 22, 1949 UNITED STATES FILAMENT CONNECTEON FOR ELECTRIC INCANDESCENT LAMPS Leroy G. Leighton, Cleveland, Ohio, vassignor to General Electric Company, a corporation of New York 4 Claims.

My invention relates ingeneral to electric incandescent lamps and similar devices especially of the high wattage type, and more particularly to a filament joint therefor.

In certain types of lamps, a segmented filament is wound with an extra coiled segment on each end of the coil proper. It has always been diflicult to make a good electrical connection between these coiled end segments and the current leads.

It is an object of my invention to provide an improved filament joint for such electric incandescent lamps or devices which will provide a good mechanical and electrical connection of the filament to the leading-in conductors of such device.

Another object of my invention is to provide a current supply connection to the end coil of an incandescent lamp filament which will assure positive short-circuit of the turns of the filament end coil and therefore a uniform effective length for the filament of each lamp.

A feature of the invention is the provision of a filament end coil and a compression coil which are screwed together throughout a portion only of the length of the compression coil and which are compressed between shoulders on an insert plug or wire spud extending through the coils and fastened to a leading-in conductor of the lamp.

Further objects and advantages of my invention will appear from the following detailed descript-ion of species thereof and from the accompanying drawing in which:

Fig. l is an elevation, partly in section, ,of an electric incandescent lamp provided with a filament joint comprising my invention; Fig. 2 is an enlarged perspective view of the filament joint shown in Fig. 1; Fig. 3 is an enlarged elevation, partly in section, of a modified form of filament joint according to the invention; and Fig. 4 is a fragmentary elevation of another modification of the invention.

Referring to the drawing, the lamp there shown comprises a tubular glass bulb or envelope i having a reentrant stem 2 at its neck end provided with a press portion 3 through which are sealed a pair of rigid metal lead-in conductors 44 the inner portions 5 of which may be nickel. The outer ends of the conductors 4-4 are connected respectively to the shell 6 and end contact '5 of a base 8 secured to the neck of the envelope l. The inner end portions of the conductor sections 55 are bent outwardly away from each other to form laterally extending portions 9-9. The conductor sections 5-5 may be made of ,able insulating material such as glass.

2 nickel and are provided with rigid side rod or wire extensions lB-JB, of molybdenum or other suitable metal, which are securely fastened to the conductor portions 55 and extendnpar allel to one another on opposite sides of the filament Ii. The side extensions |0l0 are spot-welded to the ends of the outwardly bent p rt ons of the conductors 4-4, and the lower ends of the said extensions are bent inwardly towards one another to form laterally extending portions !Z- I2 which are also spot-welded to the conductors 44.

The particular filament IJ illustrated in the drawing is of the biplane type comprising a plurality of parallel coiled segments .of tungsten wire joined by upper and lower uncoiled or bight portions !3 and M respectively, the alternate segments of the filament being staggered so as-to lie alternately in two parallel planes. The filament H is supported ,in place by meansof a plurality of upp rand lower anchor wires I5 and I6 extending, respectively, from a stationary upper bridge member [1 and a slidable lower bridge member 18, which members are made of a suit.-

The anchor wires l5-l6 have hooked ends engaging .the bights l3-I4.ofthe fi1ament and their other ,ends :rigidly secured to the bridge members 11-48, as by embedding therein. The lower sliding bridge member I78 is supportedat its ends by end support wires |9 I-9 which are looped around the conductor extensions ;l;fl-.- l0 with a loose fit so as to slide freely therealong. The said bridge member i8 is further positioned in place at its center by means of a center support wire 20 which extends through and freely slides within a loop 2! on a guide wire 22 embedded in and upstanding from the press portion 3 of the stem 2. The upper bridge member I! is supported at its ends by short fastening wires 23-23 suitably secured, as by spot-welding, to metal connectors 24-24 which are secured to the inner ends of the side conductor extensions I0 and extend laterally therefrom towards one another.

The connectors 24 illustrated in Figs. 1 and 2 are in the form of clips or lugs 25 which are tightly pinched or clamped at one end around the conductor extensions Ill-Ill and at their other ends around wire spuds or insert plugs 26 of molybdenum, tungsten, or other suitable metal, which extend towards the base end of the lamp in parallel relation to each other. The lower or free end of each spud 29 is provided wtih an abutment or stop shoulder 21 which is preferably formed by flattening the said end of the spud (as indicated at 28) and which is opposed to the shoulder 29 formed at the other end of the'spud I by the connector 24.

The ends of the filament H are provided with coiled end portions or segments 30 each of which is screwed together with a compression coil 3| of tungsten wire preferably having a wire diameter slightly smaller than that of the tungsten filament II and a coil diameter such as will provide tight screw-mesh engagement with the filament end coil 30. The inter-threaded coils 303| fit over the spud 26 between the shoulders 21-49 thereon, with the inner one of the coils fitting the spud more or less snugly. The two coils 30 and 3| are screwed together for a portion only of the length of the compression coil 3| and preferably for a portion only of the length of the filament end coil 3|] also, as shown, and the inter-threaded coil assembly is compressed endwise between the shoulders 2l29 on the spud so as to press the first turn 32 of the filament end coil 30 tightly against the shoulder 21 on the spud, thus providing a good electrical contact therebetween at all times which serves to effectively short-circuit the remaining turns of the filament end coil. In this manner, uniform effective length of the filament I is assured in each lamp. As shown, the compression coil 3| is preferably screwed over the filament end coil 30, but this arrangement may be reversed if desired and the compression coil 3| screwed into the filament end coil instead.

In forming the filament joint according to the invention, the compression coil 3| and filament end coil 30 are first screwed together to an overall length somewhat less than the designed distance between the shoulders 2'|29. The spud 26 with its flattened end 28 is then inserted through the inter-threaded coils 30 and 3| and clamped at its other end in the connector clip 25. The two coils 30 and 3| are then partially unscrewed until the ends of the coil assembly abut against the shoulders 2'|29 and the assembly is compressed therebetween to the desired degree.

Instead of using clips 25 clamped around the lead-in conductor l and the spud 26, the connectors 24 may be constituted merely by a length of wire or a fiat strip of metal, as indicated at 33 in Fig.- 3, spot-welded at its ends to the conductor and the spud. Alternatively the lead-in conductor extensions -5 may be bent inwardly at their inner ends to form inbent portions 34 to which the spuds 26 may be spot-welded.

What I claim as new and desire to secure by Letters Patent of the United States:

1. In an electric incandescent lamp, the combination of a leading-in conductor having a spud portion provided with opposed shoulders spaced longitudinally thereof, a filament having an end coil portion fitted over the said spud portion, and a wire compression coil fitted over the said spud portion, said filament end coil and said compression coil being screwed together throughout a portion only of the length of said compression coil and being compressed between the shoulders of said spud portion.

2. In an electric incandescent lamp, the combination of a leading-in conductor having a spud portion provided with opposed shoulders spaced longitudinally thereof, a filament having an end coil portion fitted over the said spud portion, and a wire compression coil fitted over the said spud portion, said filament end coil and said compression coil being screwed together throughout a portion only of their respective lengths and being compressed between the shoulders of said spud portion.

3. In an electric incandescent lamp, the combination of a leading-in conductor having a spud portion provided with opposed shoulders spaced longitudinally thereof, a filament having an end coil portion fitted over the said spud portion, and a wire compression coil fitted'over the said spud portion and having a portion only of its length screwed over the filament end coil, said inter-threaded coils being compressed between the shoulders of said spud portion.

4. In an electric incandescent lamp, the combination of a lead-in conductor, a wire spud secured to said lead-in conductor and provided with opposed shoulders spaced longitudinally thereof, a filament having an end coil fitted over said spud between the said shoulders, and a compression coll fitted over the said spud between the said shoulders and screwed over the filament end coil, said coils being screwed together throughout a portion only of their respective lengths and being compressed between the said shoulders on the spud.

LEROY G. LEIGHTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,134,574 Pinkle Oct. 25, 1938 2,404,992 Stone July 30, 1946 

